connecting spring to shoe

Hi All,

I need to replace the coil balance shoe in my window. I purchased a replacement shoe (15-177) and a set of replacement coil balance springs (S152-6, see photo). The old springs have a notch that causes them to connect to the shoe. The new springs have a hole, but how can I fasten the new springs to the shoe, is there a fastener, like a screw, I did not purchase?

Thanks for any help.
julian